The present invention relates to a magneto-optical recorder, and more particularly to a magneto-optical recorder in which a magnetic field required for recording and erasing can be generated by a small-sized electromagnetic coil having a small magneto-motive force.
External magnetic field generating means in a conventional magneto-optical disc apparatus is described in an article entitled "Amorphous thin film disk for magneto-optical memory" (SPIE, Vol. 329, page 208, Optical Disc Technology, 1982). The conventional magneto-optical disc apparatus, as shown in FIG. 10, includes a recording-reproducing optical system 11 and an electromagnetic coil 10, and a focusing lens 5 is disposed so as to face the electromagnetic coil 10 through an optical disc 1. In this disc apparatus, the electromagnetic coil 10 for generating an external magnetic field is made up of a magnetic core 101 and a coil winding 102 provided around the core 101, or is formed of an air-core coil. Accordingly, a magnetic field 103 generated by the electromagnetic coil 10 spreads over a wide space, and hence the magnetic field 103 is low is efficiency for producing a magnetic field component H.sub.ex.perp. applied perpendicularly to a recording film 100 on the optical disc. In order to apply the magnetic field component H.sub.ex.perp. having a desired intensity to the recording film, the electromagnetic coil 10 is required to have a large magneto-motive force. This makes it impossible to make the electromagnetic coil small in size and low in power consumption.